This invention relates to plants having an increased level of resistance to a pathogen and to methods for producing them.
Grapevines are a deciduous temperate fruit crop of ancient origin. Grape production (65×106 metric tons) exceeds that of any other temperate fruit crop, and ranks third after Citrus and banana production. In addition, due to its uses for fresh fruit, juice, jelly, raisins, and wine, grapes surpass all other fruit crops in value. Therefore, successful efforts to improve grapevines are likely to have a major impact on commercial viticulture.
Current methods for improving grapevines are time-consuming and labor intensive. For example, genetic improvement in grapes through conventional breeding is severely limited by a number of factors such as long pre-bearing age and varying ploidy levels. Cultivated grapes are also highly heterozygous and do not generally breed true from seeds. Moreover, grape breeding programs are expensive, long-term projects. Although plant biotechnology is an attractive alternative for genetic improvement in grapes (Kuksova et al., Plant Cell Tiss. Org. Cult. 49:17–27, 1997), in vitro genetic manipulation can be addressed only if there is an effective regeneration system. Accordingly, methods that reduce any of these problems would represent a significant advancement in the art.